Multimedia Solved Question Papers

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DVI (Digital Visual Interface) Technology

The DVI is a video interface standard designed to provide very high visual quality on digital display devices such as flat panel LCD computer displays and digital projectors.

The DVI interface uses a digital protocol in which the desired illumination of pixels is transmitted as binary data. When the display is driven at its native resolution, it will read each number and apply that brightness to the appropriate pixel. In this way, each pixel in the output buffer of the source device corresponds directly to one pixel in the display device, whereas with an analog signal the appearance of each pixel may be affected by its adjacent pixels as well as by electrical noise and other forms of analog distortion.

Read more from Multimedia System By:- John F.Koegel Buford. Page No.181-185

MPEG VIDEO

GenXTechno Tags: mpeg, compression, i frame, p frame, b Frame

Although the MPEG-1 standard is quite flexible, the basic algorithms have been tuned to work well at data rates from 1 to 1.5 Mbps, at resolutions of about 350 by 250 Pixels at picture rates of up to 25 or 30 pictures per second. MPEG-1 codes progressively-scanned images and does not recognized the concept of interlace, interlaced source video must be converted to a non-interlace format prior to encoding. The format of the coded video allows forward play and pause, typical coding and decoding methods allow random access, fast forward and reverse play also, the requirements for these functions are very much application dependent and different encoding techniques will include varying levels of flexibility to account for these functions. Compression of the digitized video comes from the use of several techniques: Sub sampling of the chroma information to match the human visual system, differential coding to exploit spatial redundancy, motion compensation to exploit temporal redundancy, Discrete Cosine Transform (DCT) to match typical image statistics, quantization, variable length coding, entropy coding and use of interpolated pictures.
Algorithm Structure and Terminology
The MPEG hierarchy is arranged into layers (Figure 1).

This layered structure is designed for flexibility and management efficiency, each layer is intended to support a specific function i.e. the sequence layer specifies sequence parameters such as picture size, aspect ratio, picture rate, bit rate etcetera , whereas the picture layer defines parameters such as the temporal reference and picture type. This layered structure improves ro-bustness and reduces susceptibility to data corruption.
For convenience of coding, macroblocks are divided into six blocks of component Pixels four luma and two chroma (Cr and Cb) (Figure 2).

Blocks are the basic coding unit and the DCT is applied at this block level. Each block contains 64 component Pixels arranged in an 8x8 array (Figure 3).

There are four picture types : I pictures or INTRA pictures, which are coded without reference to any other pictures; P pictures or PREDICTED pictures which are coded using motion compensation from previous picture; B pictures or BIDIRECTIONALLY predicted pictures which are coded using interpolation from a previous and a future picture and D pictures or DC pictures in which only the low frequency component is coded and which are only intended for fast forward search mode. B and P pictures are often called Inter pictures. Some other terminology that is often used are the terms M and N, M+1 represents the number of frames between successive I and P pictures whereas N+1 represents the number of frames between successive I pictures. M and N can be varied according to different applications and requirements such as fast random access.
A typical coding scheme will contain a mix of I,P and B pictures. A typical scheme will have an I picture every 10 to 15 pictures and two B pictures between succesive I and P pictures (Figure 4).

Prediction (P Frame)
The predicted picture is the previous picture modified by motion compensation. Motion vectors are calculated for each macroblock. The motion vector is applied to all four luminance blocks in the macro block. The motion vector for both chrominance blocks is calculated from the luma vector. This technique relies upon the assumption that within a macroblock the difference between successive pictures can be represented simply as a vector transform (i.e. there is very little difference between successive pictures, the key difference being in position of the Pixels) (Figure 5).

Interpolation ( I Frame)
Interpolation (or bidirectional prediction) generates high compression in that the picture is represented simply as an interpolation between the past and future I or P pictures (again this is performed on a Pictures are not transmitted in display order but in the order in which the decoder requires them to decode the bitstream (the decoder must of course have the reference picture(s) before any interpolated or predicted pictures can be decoded).

 

Thnx to:-Ref:-SGS-THOMSON Microelectronics

Different Sound Spectrum

GenXTechno Tags: stereophonic, quardraphonic, sound

Stereophonic Sound

Stereophonic sound, commonly called stereo, is the reproduction of sound using two or more independent audio channels through a symmetrical configuration of loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing. It is often contrasted with monophonic or "mono" sound, where audio is in the form of one channel, often centered in the sound field (analogous to a visual field).

Recording methods

X-Y technique: intensity stereophony

A-B technique: time-of-arrival stereophony

M/S technique: Mid/Side stereophony

Near-coincident technique: mixed stereophony

Quadraphonic sound

Quadraphonic sound consists of 4 channels, right front, left front, right rear, and left rear. Quad albums and equipment starting to show up in the early '70s, and as you can probably imagine, quad albums came in primarily 3 different formats, 8 track, record, and open reel, the first 2 being the most common. The stereo 8 track, like the name says, has 8 tracks, making 4 programs (4 programs * 2 channels = 8 tracks). The quad 8 track used the same number of tracks (again, like the name says), and has only 2 programs (2 programs * 4 channels = 8 tracks). One more difference to keep in mind (one of the many reasons quad didn't stay around) is that when the number of programs is cut in half, so is the time, meaning quad 8 tracks had to have more tape to get the same play time as their stereo counterparts.
The stereo record (like all records) has a 2 sided "V" shaped grove, in which the needle rides. The stereo (and quad) records have that groove cut at a 90 degree angle, so each side is 45 degrees to the surface of the record, and each of the 2 channels in recorded it's own side of the groove. Since it isn't possible to have a groove with more than two sides that will play back right or be compatible with existing equipment, quad records use encoding and decoding to take the 4 channels of sound and make them into 2 channels to store on the record, and to then separate the 4 channels back out when it's played. Either matrixing or modulation of rear channels onto high frequencies is used to make the original 4 channels fit onto 2 (There is more about this below).

The Fourier method

GenXTechno Tags: audio, encoding, foruier

Introduction To Fourier method
The temporal analysis of a signal with the Fourier method (spectral analysis) allows us to highlight the main components of a signal. In the musical world, the spectral analysis allows us to identify different instruments: each instrument has its own particular tone.
We can "observe" the sound, which is nothing other than a movement of matter. The resonance frequencies in particular are very characteristic. A resonance vibration (or oscillation) is characterized on a chord by a succession of antinodes and nodes, i.e. of points where the vibrations have a maximal or null displacement respectively.

• The sound emitted by a diapason (A 440 Hz) corresponds to a pure sound.
• The sound of a guitar has several harmonics.
• The spectrum of a cymbal is much more complex.

When studying a signal, a sound for instance, the spectrum allows us to determine the characteristics of this signal : frequency and intensity.
In the case of the Sun or stars, which are located millions of kilometers away, how can we observe the interior of these objects, for which the temperature exceeds one million degrees?
We must listen, not try to only see, and use the sound waves.

• The light allows us to explore the surface of an object, it does not penetrate very much in depth,
• The sound gives information on the deeper layers, it propagates inside the object.

Subband Coding

mGenXTechno Tags: audio, encoding, subband, coding

Introduction to Subband Coding
Sub-Band Coding (SBC) is a powerful and general method of encoding audio signals efficiently. Unlike source specific methods (like LPC, which works only on speech), SBC can encode any audio signal from any source, making it ideal for music recordings, movie soundtracks, and the like. MPEG Audio is the most popular example of SBC. This document describes the basic ideas behind SBC and discusses some of the issues involved in its use.
Basic Principles
SBC depends on a phenomenon of the human hearing system called masking. Normal human ears are sensitive to a wide range of frequencies. However, when a lot of signal energy is present at one frequency, the ear cannot hear lower energy at nearby frequencies. We say that the louder frequency masks the softer frequencies. The louder frequency is called the masker.
The source output can be decomposed into its constituent parts using digital filters.
Each of these constituent parts will be different bands of frequencies which make up the source.
A compression approach where digital filters are used to separate the source output into different bands of frequencies.
àEach part then can be encoded separately.
Filters
A filter is system that isolates certain frequencies.
(i) Low Pass Filters
(ii) High Pass Filters
(iii) Band Pass Filters
Filter Characteristics

• ØMagnitude Transfer Function : the ratio of the magnitude of the input and output of the filter as a function of frequency.

• fo = Cutoff Frequency.

Digital Filters
Components between frequencies f1and f2 then,
Sampling and Nyquist rule :
If fo is the highest frequency of the signal then the sampling rate > 2fo per second can accurately represent the continuous signal in digital form.
Extension of Nyquist rule:
For signal with frequency
sampling rate = 2(f2 — f1) per second.
Violation of Nyquist rule:
Distortion due to aliasing.



Subband Coding Algorithm



Above picture shows pyramid decomposition of an image where encoding is shown on the left and decoding is shown on the right. The operators D and I correspond to Decimation and interpolation operators, respectively. For example, D produces an N/2 × N/2 image from an N × N original, while I interpolate an N × N image based on an N/2 × N/2 original.
Analysis
Source output --> analysis filter bank--> sub-sampled-->encoded.
Analysis Filter Bank

• The source output is passed through a bank of filters.
• his filter bank covers the range of frequencies that make up the source output.
• The passband of each filter specifies each set of frequencies that can pass through.

Decimation

• The outputs of the filters are subsampled thus reducing the number of samples.
• The justification for the subsampling is the Nyquist rule and its extension justifies this downsampling.
• The amount of decimation depends on the ratio of the bandwidth of the filter output to the filter input.

Encoding

• The decimated output is encoded using one of several encoding schemes, including ADPCM, PCM, and vector quantization.

Quantization and Coding
Selection of the compression scheme will be done based on the characteristic exhibited by the subbands.
Along with the selection of the compression scheme, the allocation of bits between the subbands is an important design parameter. This is what determines the quantizer parameters.

• Selection of the compression scheme
• Allocation of bits between the subbands

-->allocate the available bits among the subbands according to measure of the information content in each subband.
Bit Allocation
This bit allocation procedure significantly impacts quality of the final reconstruction.
Minimizing the distortion i.e. minimizing the reconstruction error drives the bit allocation procedure.
Different subband-->different amount of information.
Bit allocation procedure can have a significant impact on the quality of the final reconstruction
Synthesis

• Quantized and Coded coefficients are used to reconstruct a representation of the original signal at the decoder.

Encoded samples from each subband—>decoded—>upsampled--> bank of reconstruction filters-->outputs combined--> Final reconstructed output

Application
The subband coding algorithm has applications in -

• Speech Coding
• Audio Coding
• Image Compression

MPEG VIDEO OVERVIEW

GenXTechno Tags: mpeg, motion, picture, expert, group, video, compression

Although the MPEG-1 standard is quite flexible, the basic algorithms have been tuned to work well at data rates from 1 to 1.5 Mbps, at resolutions of about 350 by 250 Pixels at picture rates of up to 25 or 30 pictures per second. MPEG-1 codes progressively-scanned images and does not recognized the concept of interlace, interlaced source video must be converted to a non-interlace format prior to encoding. The format of the coded video allows forward play and pause, typical coding and decoding methods allow random access, fast forward and reverse play also, the requirements for these functions are very much application dependent and different encoding techniques will include varying levels of flexibility to account for these functions. Compression of the digitized video comes from the use of several techniques: Sub sampling of the chroma information to match the human visual system, differential coding to exploit spatial redundancy, motion compensation to exploit temporal redundancy, Discrete Cosine Transform (DCT) to match typical image statistics, quantization, variable length coding, entropy coding and use of interpolated pictures.
Algorithm Structure and Terminology
The MPEG hierarchy is arranged into layers (Figure 1).

This layered structure is designed for flexibility and management efficiency, each layer is intended to support a specific function i.e. the sequence layer specifies sequence parameters such as picture size, aspect ratio, picture rate, bit rate etcetera , whereas the picture layer defines parameters such as the temporal reference and picture type. This layered structure improves ro-bustness and reduces susceptibility to data corruption.
For convenience of coding, macroblocks are divided into six blocks of component Pixels four luma and two chroma (Cr and Cb) (Figure 2).

Blocks are the basic coding unit and the DCT is applied at this block level. Each block contains 64 component Pixels arranged in an 8x8 array (Figure 3).

There are four picture types : I pictures or INTRA pictures, which are coded without reference to any other pictures; P pictures or PREDICTED pictures which are coded using motion compensation from previous picture; B pictures or BIDIRECTIONALLY predicted pictures which are coded using interpolation from a previous and a future picture and D pictures or DC pictures in which only the low frequency component is coded and which are only intended for fast forward search mode. B and P pictures are often called Inter pictures. Some other terminology that is often used are the terms M and N, M+1 represents the number of frames between successive I and P pictures whereas N+1 represents the number of frames between successive I pictures. M and N can be varied according to different applications and requirements such as fast random access.
A typical coding scheme will contain a mix of I,P and B pictures. A typical scheme will have an I picture every 10 to 15 pictures and two B pictures between succesive I and P pictures (Figure 4).

Prediction (P Frame)
The predicted picture is the previous picture modified by motion compensation. Motion vectors are calculated for each macroblock. The motion vector is applied to all four luminance blocks in the macro block. The motion vector for both chrominance blocks is calculated from the luma vector. This technique relies upon the assumption that within a macroblock the difference between successive pictures can be represented simply as a vector transform (i.e. there is very little difference between successive pictures, the key difference being in position of the Pixels) (Figure 5).

Interpolation ( I Frame)
Interpolation (or bidirectional prediction) generates high compression in that the picture is represented simply as an interpolation between the past and future I or P pictures (again this is performed on a Pictures are not transmitted in display order but in the order in which the decoder requires them to decode the bitstream (the decoder must of course have the reference picture(s) before any interpolated or predicted pictures can be decoded).

MULTIMEDIA DATABASE SYSTEM

GenXTechno Tags: multimedia, database, system, server

A multimedia database is a database
that hosts one or more primary media file types such as .txt (documents), .jpg (images), .swf (videos), .mp3 (audio), etc. And loosely fall into three main categories:

• Static media (time-independent, i.e. images and handwriting)
• Dynamic media (time-dependent, i.e. video and sound bytes)
• Dimensional media (i.e. 3D games or computer-aided drafting programs- CAD)

All primary media files are stored in binary strings of zeros and ones, and are encoded according to file type.
The term "data" is typically referenced from the computer point of view, whereas the term "multimedia" is referenced from the user point of view.

Types of Multimedia Databases

There are numerous different types of multimedia databases, including:

• The Authentication Multimedia Database (also known as a Verification Multimedia Database, i.e. retina scanning), is a 1:1 data comparison
• The Identification Multimedia Database is a data comparison of one-to-many (i.e. passwords and personal identification numbers
• A newly-emerging type of multimedia database, is the Biometrics Multimedia Database; which specializes in automatic human verification based on the algorithms of their behavioral or physiological profile.

This method of identification is superior to traditional multimedia database methods requiring the typical input of personal identification numbers and passwords-
Due to the fact that the person being identified does not need to be physically present, where the identification check is taking place.
This removes the need for the person being scanned to remember a PIN or password. Fingerprint identification technology is also based on this type of multimedia database.

Difficulties Involved with Multimedia Databases

The difficulty of making these different types of multimedia databases readily accessible to humans is:

• The tremendous amount of bandwidth they consume;
• Creating Globally-accepted data-handling platforms, such as Joomla, and the special considerations that these new multimedia database structures require.
• Creating a Globally-accepted operating system, including applicable storage and resource management programs need to accommodate the vast Global multimedia information hunger.
• Multimedia databases need to take into accommodate various human interfaces to handle 3D-interactive objects, in an logically-perceived manner (i.e. SecondLife.com).
• Accommodating the vast resources required to utilize artificial intelligence to it's fullest potential- including computer sight and sound analysis methods.
• The historic relational databases (i.e the Binary Large Objects - BLOBs- developed for SQL databases to store multimedia data) do not conveniently support content-based searches for multimedia content.

This is due to the relational database not being able to recognize the internal structure of a Binary Large Object and therefore internal multimedia data components cannot be retrieved...
Basically, a relational database is an "everything or nothing" structure- with files retrieved and stored as a whole, which makes a relational database completely inefficient for making multimedia data easily accessible to humans.
In order to effectively accommodate multimedia data, a database management system, such as an Object Oriented Database (OODB) or Object Relational Database Management System (ORDBMS).
Examples of Object Relational Database Management Systems include Odaptor (HP): UniSQL, ODB-II, and Illustra.
The flip-side of the coin, is that unlike non-multimedia data stored in relational databases, multimedia data cannot be easily indexed, retrieved or classified, except by way of social bookmarking and ranking-rating, by actual humans.
This is made possible by metadata retrieval methods, commonly referred to as tags, and tagging. This is why you can search for dogs, as an example, and a picture comes up based on your text search tem.
This is also referred to a schematic mode. Whereas doing a search with a picture of a dog to locate other dog pictures is referred to as paradigmatic mode.
However, metadata retrieval, search, and identify methods severely lack in being able to properly define uniform space and texture descriptions, such as the spatial relationships between 3D objects, etc.
The Content-Based Retrieval multimedia database search method (CBR), however, is specifically based on these types of searches. In other words, if you were to search an image or sub-image; you would then be shown other images or sub-images that related in some way to your the particular search, by way of color ratio or pattern, etc.





MULTIMEDIA DATABASE SERVER
Characteristics of Multimedia Data

• Large number of objects
• Large object sizes
• Very high dimensionality
• Retrieval by content
• Similar by not exactly the same
• Real-time constraints
• Spatial and temporal dependencies e.g., as in video data

Features of a Multimedia Server

• Support for a variety of multimedia types and formats
• Real-time guarantees
• Scalable
• Reliable

Client/Server Multimedia System

• Centralized server
• Uses the server host to perform all of file system functions
• Storage elements behind the server
• Server becomes bottleneck with increasing users

Scalability of a Multimedia Server

• Scale up with increasing user pool
• Should not involve centralized entity
• Distribute work among participating entities
• Provide real-timeliness

Architecture for Distributed Multimedia Server

Image File Formats

GenXTechno Tags: image, format, gif, tiff, bmp, png, cgm

GIF
GIF was developed by CompuServe to show images online (in 1987 for 8 bit video boards, before JPG and 24 bit color was in use). GIF uses indexed color, which is limited to a palette of only 256 colors (next page). GIF was a great match for the old 8 bit 256 color video boards, but is inappropriate for today's 24 bit photo images.
GIF files do NOT store the image's scaled resolution ppi number, so scaling is necessary every time one is printed. This is of no importance for screen or web images. GIF file format was designed for CompuServe screens, and screens don't use ppi for any purpose. Our printers didn't print images in 1987, so it was useless information, and CompuServe simply didn't bother to store the printing resolution in GIF files.
GIF is still an excellent format for graphics, and this is its purpose today, especially on the web. Graphic images (like logos or dialog boxes) use few colors. Being limited to 256 colors is not important for a 3 color logo. A 16 color GIF is a very small file, much smaller, and more clear than any JPG, and ideal for graphics on the web.

Tag Image File Format (TIFF)

Many image file formats have an image header with fixed fields containing information such as image dimensions, color space specification, etc. The TIFF file format is different in that it allows for a flexible set of information fields. There exists a specification for many of these information fields, called 'tags', ranging from the most fundamental, like image dimensions, over the most luxurious like copyright information, up to so-called 'private tags' or 'custom tags' that you can define to hold your own application specific information. The TIFF specification defines a framework for an image header called 'IFD' (Image File Directory) that is essentially a flexible set of specifically those tags that the TIFF writer software wishes to specify.
One final important difference between TIFF and most other image file formats is that TIFF defines support for multiple images in a single file. Such a file is then called 'multi-page' TIFF. Thus, the TIFF format is very well suited to e.g. store the many pages of a single fax in a single file.
Another major difference between most other image file formats and TIFF, is that TIFF allows for a wide range of different compression schemes and color spaces.
BMP
BMP is a standard file format for computers running the Windows operating system. The format was developed by Microsoft for storing bitmap files in a device-independent bitmap (DIB) format that will allow Windows to display the bitmap on any type of display device. The term “device independent” means that the bitmap specifies pixel color in a form independent of the method used by a display to represent color.

General information

Since BMP is a fairly simple file format, its structure is pretty straightforward. Each bitmap file contains:

• a bitmap-file header: this contains information about the type, size, and layout of a device-independent bitmap file.
• a bitmap-information header which specifies the dimensions, compression type, and color format for the bitmap.
• a colour table, defined as an array of RGBQUAD structures, contains as many elements as there are colours in the bitmap. The colour table is not present for bitmaps with 24 color bits because each pixel is represented by 24-bit red-green-blue (RGB) values in the actual bitmap data area.
• an array of bytes that defines the bitmap bits. These are the actual image data, represented by consecutive rows, or “scan lines,” of the bitmap. Each scan line consists of consecutive bytes representing the pixels in the scan line, in left-to-right order.

BMP files always contain RGB data. The file can be:

• 1-bit: 2 colors (monochrome)
• 4-bit: 16 colors
• 8-bit: 256 colors.
• 24-bit: 16777216 colors, mixes 256 tints of Red with 256 tints of Green and Blue

Portable Network Graphics (PNG)

The Portable Network Graphics (PNG) format was designed to replace the older and simpler GIF format and, to some extent, the much more complex TIFF format.
PNG really has three main advantages over GIF: alpha channels (variable transparency), gamma correction (cross-platform control of image brightness), and two-dimensional interlacing (a method of progressive display). PNG also compresses better than GIF in almost every case, but the difference is generally only around 5% to 25%, not a large enough factor to encourage folks to switch on that basis alone. One GIF feature that PNG does not try to reproduce is multiple-image support, especially animations; PNG was and is intended to be a single-image format only.
CGM (Computer Graphics Metafile)

It was specifically designed as a common format for the platform-independent interchange of bitmap and vector data, and for use in conjunction with a variety of input and output devices.
CGM uses three types of syntactical encoding formats. All CGM files contain data encoded using one of these three methods:

• Character-based, used to produce the smallest possible file size for ease of storage and speed of data transmission
• Binary encoded, which facilitates exchange and quick access by software applications
• Clear-text encoded, designed for human readability and ease of modification using an ASCII text editor

CGM is intended for the storage of graphics data only. It is sometimes (erroneously) thought to be a data transfer standard for CAD/CAM data, like IGES, or a 3D graphic object model data storage standard. However, CGM is quite suited for the interchange of renderings from CAD/CAM systems, but not for the storage of the engineering model data itself.

Scalable Vector Graphics (SVG)

SVG is a language for describing two-dimensional graphics and graphical applications in XML. SVG 1.1 is a W3C Recommendation and is the most recent version of the full specification. SVG Tiny 1.2 is a W3C Recommendation, and targets mobile devices. There are various SVG modules under development which will extend previous versions of the specification, and which will serve as the core of future SVG developments.

Video on Demand

mGenXTechno Tags: video, demand, video on demand, load, distribution, server

Pay-per-view (PPV) services could be considered a primitive form of distributing media on demand. This requires the subscriber to sign-up for an account and thus enabling him access the service. The subscriber is being charged for installation and a periodic rental. This scheme is different from pure broadcast in the sense that it provides the subscriber the control to receive according to his subscription.
Quasi Video-on-Demand (Q-VoD) services, takes selective subscription a little more ahead by multicasting media content amongst a group of users who share a common set of interests. To access media content that is not available in a particular group a subscriber belongs to, he can switch between groups. Near video-on-demand (N-VoD) services simulate media access control functions like forward and reverse in discrete time intervals. This capability is usually facilitated by providing multiple channels with the same media content, skewed in time.
All these concepts collate to the introduction of a True Video on Demand system. To provide control to the subscriber, a True Video-on-demand system requires a feedback mechanism installed at the subscriber device that aids the Video-on Demand service engine control the rate of data transfer over the network. Thus depending on the network bandwidth the service provider, signals the underlying encoding engine to manipulate the media encoding bit rate so that media can be delivered to the subscriber trading off between the quality or the request-response latency.
The Challenges
1. Load distribution on server: To support multiple connection requests from user, and facilitate minimum response time.
2. Media content management: This includes high storage space, effective content management, replication strategy etc.
3. Adapt to dynamic network bandwidth: As the client-server link may not always be consistent, one needs to manage the content corresponding to network change and still maintain quality of the media.
4. Decide on Buffer/Cache: To facilitate user with better quality and high-response time, the system may have to decide upon the buffer size and cache.
5. Rate control: For adapting to network, the system may need to vary the transport and encoding rates.
6. Scalability and cost effectiveness.
7. To provide reliability and availability
In addition to these parameters, such a set-up needs to be highly fault-tolerant and fairly scalable to ensure subscriber satisfaction. Several architectures are proposed in this regard which address the above mentioned issues by employing expensive hardware infrastructure.

Computer Graphics

GenXTechno Tags: graphics, 3d, morphing, shading, anti, aliasing

Computer displays are made up from grids of small rectangular cells called pixels. The picture is built up from these cells. The smaller and closer the cells are together, the better the quality of the image, but the bigger the file needed to store the data. If the number of pixels is kept constant, the size of each pixel will grow and the image becomes grainy (pixellated) when magnified, as the resolution of the eye enables it to pick out individual pixels.
Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical equations, to represent images in computer graphics.
Vector graphics files store the lines, shapes and colours that make up an image as mathematical formulae. A vector graphics program uses these mathematical formulae to construct the screen image, building the best quality image possible, given the screen resolution. The mathematical formulae determine where the dots that make up the image should be placed for the best results when displaying the image. Since these formulae can produce an image scalable to any size and detail, the quality of the image is only determined by the resolution of the display, and the file size of vector data generating the image stays the same. Printing the image to paper will usually give a sharper, higher resolution output than printing it to the screen but can use exactly the same vector data file.
3D Graphics

A picture that has or appears to have height, width and depth is three-dimensional (or 3-D). A picture that has height and width but no depth is two-dimensional (or 2-D).

Take a look at the triangles above. Each of the triangles on the left has three lines and three angles -- all that's needed to tell the story of a triangle. We see the image on the right as a pyramid -- a 3-D structure with four triangular sides. Note that it takes five lines and six angles to tell the story of a pyramid -- nearly twice the information required to tell the story of a triangle.

What Are 3-D Graphics?

For many of us, games on a computer or advanced game system are the most common ways we see 3-D graphics. These games, or movies made with computer-generated images, have to go through three major steps to create and present a realistic 3-D scene:

1. Creating a virtual 3-D world.
2. Determining what part of the world will be shown on the screen.
3. Determining how every pixel on the screen will look so that the whole image appears as realistic as possible.

What Is Animation?

What is animation? To put it simply, animation is the illusion of movement. When you watch television, you see lots of things moving around. You are really being tricked into believing that you are seeing movement. In the case of television, the illusion of movement is created by displaying a rapid succession of images with slight changes in the content. The human eye perceives these changes as movement because of its low visual acuity. The human eye can be tricked into perceiving movement with as low as 12 frames of movement per second. It should come as no surprise that frames per second (fps) is the standard unit of measure for animation. It should also be no surprise that computers use the same animation technique as television sets to trick us into seeing movement.

Types of Animation

Frame-Based Animation

Frame-based animation is the simpler of the animation techniques. It involves simulating movement by displaying a sequence of static frames. A movie is a perfect example of frame-based animation; each frame of the film is a frame of animation. When the frames are shown in rapid succession, they create the illusion of movement. In frame-based animation, there is no concept of an object distinguishable from the background; everything is reproduced on each frame. This is an important point, because it distinguishes frame-based animation from cast-based animation.

Cast-Based Animation

Cast-based animation, which also is called sprite animation, is a very popular form of animation and has seen a lot of usage in games. Cast-based animation involves objects that move independently of the background. At this point, you may be a little confused by the use of the word "object" when referring to parts of an image. In this case, an object is something that logically can be thought of as a separate entity from the background of an image. For example, in the animation of a forest, the trees might be part of the background, but a deer would be a separate object moving independently of the background.
Each object in a cast-based animation is referred to as a sprite, and can have a changing position. Almost every video game uses sprites to some degree. For example, every object in the classic Asteroids game is a sprite moving independently of the other objects. Sprites generally are assigned a position and a velocity, which determine how they move.

Sprite Animation

Sprite animation involves the movement of individual graphic objects called sprites. Unlike simple frame animation, sprite animation involves considerably more overhead. More specifically, it is necessary not only to develop a sprite class, but also a sprite management class for keeping up with all the sprites. This is necessary because sprites need to be able to interact with each other through a common interface.
Shading

Shading is a process used in drawing for depicting levels of darkness on paper by applying media more densely or with a darker shade for darker areas, and less densely or with a lighter shade for lighter areas.
Flat shading

• Entire surface (polygon) has one colour
• Cheapest to compute, and least accurate (so you need a dense triangulation for decent-looking results)
• OpenGL – glShadeModel(GL_FLAT)

Phong shading

• Compute illumination for every pixel during scan conversion
• Interpolate normal at each pixel too
• Expensive, but more accurate
• Not supported in OpenGL (directly)

Gouraud shading

• Just compute illumination at vertices
• Interpolate vertex colours across polygon pixels
• Cheaper, but less accurate (spreads highlights)
• OpenGL - glShadeModel(GL_SMOOTH)

Phong illumination

• Don’t confuse shading and illumination!
• Shading describes how to apply an illumination model to a polygonal surface patch
• All these shading methods could use Phong illumination (ambient, diffuse, and specular) or any other local illumination model

Anti-Aliasing
anti-aliasing is the technique of minimizing the distortion artifacts known as aliasing when representing a high-resolution signal at a lower resolution. Anti-aliasing is used in digital photography, computer graphics, digital audio, and many other applications.
Anti-aliasing means removing signal components that have a higher frequency than is able to be properly resolved by the recording (or sampling) device. This removal is done before (re)sampling at a lower resolution. When sampling is performed without removing this part of the signal, it causes undesirable artifacts such as the black-and-white noise near the top of figure 1-a below.

Aliasing Anti-Aliased Anti-Aliased
Another method for reducing jaggies is called smoothing, in which the printer changes the size and horizontal alignment of dots to make curves smoother.
Antialiasing is sometimes called oversampling.
Morphing
Morphing is a special effect in motion pictures and animations that changes (or morphs) one image into another through a seamless transition.
Morphing is an image processing technique used for the metamorphosis from one image to another. The idea is to get a sequence of intermediate images which when put together with the original images would represent the change from one image to the other. The simplest method of transforming one image into another is to cross-dissolve between them. In this method, the color of each pixel is interpolated over time from the first image value to the corresponding second image value. This is not so effective in suggesting the actual metamorphosis. For morphs between faces, the metamorphosis does not look good if the two faces do not have the same shape approximately.


The following examples show some of the uses of warping. The first set of images shows how facial features and/or expressions can be manipulated. The second set shows how the overall shape of the image can be distorted (e.g., to match the shape of a second image for use in the morphing algorithm).

Multimedia

GenXTechno Tags: multimedia, applications, framework, distributed, processing, system, information, model

Multimedia is media and content that uses a combination of different content forms. The term can be used as a noun (a medium with multiple content forms) or as an adjective describing a medium as having multiple content forms. The term is used in contrast to media which only use traditional forms of printed or hand-produced material. Multimedia includes a combination of text, audio, still images, animation, video, and interactivity content forms.

Definitions:-

“As the name implies, multimedia is the integration of multiple forms of media. This includes text, graphics, audio, video, etc”.

For example, a presentation involving audio and video clips would be considered a "multimedia presentation." Educational software that involves animations, sound, and text is called "multimedia software." CDs and DVDs are often considered to be "multimedia formats" since they can store a lot of data and most forms of multimedia require a lot of disk space.

“Information in more than one form. It includes the use of text, audio, graphics, animation and full-motion video. Multimedia programs are typically games, encyclopedias and training courses on CD-ROM or DVD. However, any application with sound and/or video can be called a multimedia program.”

History of the term

The term "multimedia" was coined by Bob Goldstein (later 'Bobb Goldsteinn') to promote the July 1966 opening of his "LightWorks at L'Oursin" show at Southampton, Long Island. On August 10, 1966, Richard Albarino of Variety borrowed the terminology, reporting: “Brainchild of songscribe-comic Bob (‘Washington Square’) Goldstein, the ‘Lightworks’ is the latest multi-media music-cum-visuals to debut as discotheque fare.”. Two years later, in 1968, the term “multimedia” was re-appropriated to describe the work of a political consultant, David Sawyer, the husband of Iris Sawyer—one of Goldstein’s producers at L’Oursin.

Multimedia Application

Multimedia can be used for entertainment, corporate presentations, education, training, simulations, digital publications, museum exhibits and so much more. With the advent multimedia authoring applications like Flash, Shockwave and Director amongst a host of other equally enchanting applications, your multimedia end product is only limited by your imagination.

Multimedia Education

Definition: Multimedia combines five basic types of media into the learning environment: text, video, sound, graphics and animation, thus providing a powerful new tool for education.

Classroom Architecture and Resources

Contents:

• 
  
  The Trend Towards Online Multimedia Education and Its Advantages Over Traditional Methods
• 
  
  Framework of an Online Multimedia Education System
• 
  
  Innovative Item Types for Learning and Testing
• 
  
  Educational Games
• 
  
  Item Shells for Automatic Generation of Multiple Items
• 
  
  Testing Intelligence and Problem Solving Skills
• 
  
  Student Modeling
• 
  
  Adaptive Testing and Item Response Theory
• 
  
  Educational Item Authoring
• 
  
  Multimedia Education on Mobile Devices
• 
  
  Human Computer Interaction, Affective Education and User Evaluation

Multimedia Design Training

Multimedia presentations are a great way to introduce new concepts or explain a new technology. In companies, this reduces the desi Design and Training time of multimedia. Individuals find it easy to understand and use.

Multimedia Entertainment

The field of entertainment uses multimedia extensively. One of the earliest applications of multimedia was for games. Multimedia made possible innovative and interactive games that greatly enhanced the learning experience. Games could come alive with sounds and animated graphics.

Multimedia Business

Even basic office applications like a word processing package or a spreadsheet tool becomes a powerful tool with the aid of multimedia business. Pictures, animation and sound can be added to these applications, emphasizing important points in the documents.

Miscellaneous

Virtual reality is a truly absorbing multimedia application. It is an artificial environment created with computer hardware and software. It is presented to the user in such a way that it appears and feels real. In virtual reality, the computer controls three of the five senses. Virtual reality systems require extremely expensive hardware and software and are confined mostly to research laboratories.

Another multimedia application is videoconferencing. Videoconferencing is conducting a conference between two or more participants at different sites by using computer networks to transmit audio and video data.

Multimedia Systems and Multimedia Programming

A complex multimedia production, whether a video game, a multimedia encyclopaedia or a “location-based entertainment environment,” often requires the concerted effort of large teams of people. Like film and video production, multimedia production calls upon the talents of artists, actors, musicians, script writers, editors and directors. These people, responsible for “content design” to use current terminology, create raw material and prepare it for presentation and interaction. In doing so they rely on multimedia authoring environments to edit and compose digital media.

The authoring environments used for multimedia production are examples of multimedia systems . Some other examples are:

• multimedia database systems — used to store and retrieve, or better, to “play” and “record” digital media;

• hypermedia systems — used to navigate through interconnected multimedia material;

• video-on-demand systems — used to deliver interactive video services over widearea networks.

The design and implementation of the above systems, and other systems dealing with digital media, forms the domain of multimedia programming.

Multimedia programming is based on the manipulation of media artefacts through software. One of the most important consequences arising from the digitization of media is that artefacts are released from the confines of studios and museums and can be brought into the realm of software. For instance, the ordinary spreadsheet or word processor no longer need content itself with simple text and graphics, but can embellish its appearance with high-resolution colour images and video sequences. (Although the example is intended somewhat facetiously, we should keep in mind that digital media offer many opportunities for abuse. Just as the inclusion of multiple fonts in document processing systems led to many “formatting excesses,” so the ready availability of digital media can lead to their gratuitous use.)

With the appearance of media art facts in software applications, programmers are faced with new issues and new problems. Although recent work in data encoding standards, operating system design and network design has identified a number of possible services for supporting multimedia applications, the application programmer must still be aware of the capabilities and limitations of these services. Issues influencing application design include:

• Media composition — digital media can be easily combined and merged. Among the composition mechanisms found in practice are: spatial composition (the document metaphor) which deals with the spatial layout of media elements; temporal composition (the movie metaphor) considers the relative positioning of media elements along a temporal dimension; procedural composition (the script metaphor) describes actions to be performed on media elements and how media elements react to events; and semantic composition (the web metaphor) establishes links between related media elements.

• Media synchronisation — media processing and presentation activities often have synchronisation constraints [10][13]. A familiar example is the simultaneous playback of audio and video material where the audio must be “lip synched” with the video. In general, synchronisation cannot be solved solely by the network or operating system and, at the very least, application developers must be aware of the synchronisation requirements of their applications and be capable of specifying these requirements to the operating system and network.

• User-interfaces — multimedia enriches the user-interface but complicates implementation since a greater number of design choices are available. For example, questions of “look-and-feel” and interface aesthetics must now take into account audio, video and other digital media, instead of just text and graphics. Multimodal interaction [2], where several “channels” can be used for information presentation, is another challenge in the design of multimedia user-interfaces.

• Compression schemes — many techniques are currently used, some standard and some proprietary, for the compression of digital audio and video data streams. Application developers need to be aware of the various performances and quality trade-offs among the numerous compression schemes.

• Database services — application programming interfaces (APIs) for multimedia databases are likely to differ considerably from the APIs of both traditional databases and the more recent object-oriented databases. For example, it has been argued that multimedia databases require asynchronous, multithreaded APIs [6] as opposed to the more common synchronous and single-threaded APIs (where the application sends the database a request and then waits for the reply). The introduction of concurrency and asynchrony has a major impact on application architecture.

• Operating system and network services — recent work on operating system support for multimedia — see Tokuda [14] for an overview — proposes a number of new services such as real-time scheduling and stream operations for time-based media. Similarly, research on “multimedia networks” (e.g. [4], [12]) introduces new services such as multicasting and “quality of service” (QoS) guarantees. Developers must consider these new services and their impact on application architecture.

• Platform heterogeneity — cross-platform development, and the ability to easily port an application from one platform to another, are important for the commercial success of multimedia applications. It is also desirable that multimedia applications adapt to performance differences on a given platform (such as different processor speeds, device access times and display capabilities).

In summary, a rich set of data representation, user interface, application architecture, performance and portability issues face the developers of multimedia systems. What we seek from environments for multimedia programming are high-level software abstractions that help developers explore this wide design space.

Multimedia Frameworks

We now look at a particular multimedia framework — one that provides explicit support for component-oriented software development. This framework is described more fully elsewhere [5]. In essence it consists of four main class hierarchies: media classes, transform classes, format classes and component* classes discuss below.

• Media classes correspond to audio, video and the other media types. Instances of these classes are particular media values — what were called media artefacts earlier in the chapter.

• Transform classes represent media operations in a flexible and extensible manner. For example, many image editing programs provide a large number of filter operations with which to transform images. These operations could be represented by methods of an image class; however, this makes the image class overly complicated and adding new filter operations would require modifying this class. These problems are avoided by using separate transform classes to represent filter operations.

• Format classes encapsulate information about external representations of media values. Format classes can be defined for both file formats (such as GIF and TIFF, two image file formats) and for “stream” formats (for instance, CCIR 601 4:2:2, a stream format for uncompressed digital video).

• Component classes represent hardware and software resources that produce, consume and transform media streams. For instance, a CD-DA player is a component that produces a digital audio stream (specifically, stereo 16 bit PCM samples at 44.1 kHz).

Components are central to the framework for two reasons. First, the framework is adapted to a particular platform by implementing component classes that encapsulate the media processing services found on the platform. Second, applications are constructed by instantiating and connecting components. The remainder of this section looks at compo-nents in more detail.

Media

Text

Image

Binary Image

Gray Scale Image

Colour Image

Graphic

2dGraphic

3dGraphic

Temporal Media

Audio

Raw Audio

Compressed Audio

Video

Raw Video

Compressed Video

Animation

Event Based Animation

Scene Based Animation

Music

Event Based Music
Score Based Music

Transform

Image Transform

Audio Transform

Video Transform

Format

Text Format

Image Format

Graphic Format

Temporal Media Format

Audio Format

Video Format

Animation Format

Music Format

Component

Producer

Consumer

Transformer

Multimedia Authoring

Definition: Multimedia authoring involves collating, structuring and presenting information in the form of a digital multimedia, which can incorporate text, audio, and still and moving images.

The driving force behind all authoring is the human need to communicate. Verbal, pictorial, sign and written languages have provided the means to communicate meaning since time immemorial. Today we can employ multimedia systems to combine text, audio, still and moving images to communicate. Computer-based digital multimedia systems not only provide the means to combine these multiple media elements seamlessly, but also offer multiple modalities for interacting with these elements. The cross-product of these multiple elements and modalities gives rise to a very large number of ways in which these can be combined.

Who is the Author?

A movie is created by a series of transformations. The inspiration and ideas for a story come from life. The Writer uses life experiences to create a story plot; at this stage the Writer is a user, while Life is the author. The Writer then writes a film script, or screenplay, which is used by the Director. Then the Director becomes the author of the raw footage based on the script. Often people consider the Director as the ultimate author of a movie; if this was true, then we should all be happy watching the raw footage. It is the Editor who puts this raw footage together to make the complete movie that can be watched as a meaningful presentation. Therefore, we can say that the Editor is the final author of the movie. However, with a videocassette or a DVD, the Borrower can use the remote control and change the order in which the various scenes are viewed. Now the Borrower is the author, and the other home viewers (deprived of the remote control) are the Users.

Interactive multimedia systems provide the users with the ability to change the presented content, making them the final Authors of the presentation. However, with the ability to easily manipulate multimedia content, new collaborative authoring paradigms are constantly being invented, based on the ideas of remixing and Open Source software.

Authoring Dimensions

These three dimensions, namely, temporal, spatial and digital dimensions are not entirely orthogonal. Therefore, changes in one dimension can effect the composition in the other dimensions.

The temporal dimension relates to the composition of the multimedia presentation in time. The main aspect of the temporal composition is the narrative, which is akin to the plot of a story. In traditional media – such as a novel or a movie – the narrative is fixed, and the user is expected to traverse the narrative as per the predetermined plot. In interactive multimedia systems, the user is given the ability to vary the order in which the content is presented; in other words, the user can change the narrative. The Movement Oriented Design (MOD) paradigm provides a model for the creation of temporal composition of multimedia systems.

The spatial dimension deals with the placement and linking of the various multimedia elements on each ‘screen’. This is similar to the concept of mis e scéne used by the film theorists. In a time varying presentation – such as a movie or an animation – the spatial composition changes continuously: most of the time the change is smooth, and at other times the change is abrupt, i.e. a change of scene. The spatial composition at any point in time must relate to the narrative, or the plot of the temporal composition, while fulfilling the aims and objects of the system. The Multimedia Design and Planning Pyramid (MUDPY) model provides a framework for developing the content starting with a concept.

The digital dimension relates to coding of multimedia content, its meta-data, and related issues. Temporal and spatial composition was part of pre-digital multimedia designs as well, e.g. for films, slide shows, and even the very early multimedia projection systems called the Magic Lantern. The digital computer era, particularly over the last two decades has provided much greater freedom in coding, manipulating, and composing digitized multimedia content. This freedom brings with it the responsibility of providing meaningful content that does not perform fancy ‘bells and whistles’ (e.g. bouncing letter, or dancing eyeballs) just for the sake of it. The author must make sure that any digital artifact relates to the aims and objectives of the presentation.

Authoring Processes

Authors aim to convey some ideas or new meanings to their audience. All authoring systems require a process that the author needs to follow, to effectively convey their ideas to the consumers of the content. Novels, movies, plays are all ‘Cultural Interfaces’ that try to tell a story. Models of processes for creating good stories have been articulated for thousands of years. Nonetheless, some scholars stand out, such as Aristotle, who over 2300 years ago wrote Poetics, a seminal work on authoring. Robert McKee details story authoring processes as applied to screenplay writing. Michael Tierno shows how Aristotle’s ideas for writing tragedies can be applied to creating good screenplays. Dramatica is a new theory of authoring, based on the problem solving metaphor.

Processes involved in creating a meaningful digital multimedia presentation have evolved from the processes used in other media authoring systems; and some of these are used as metaphors for underpinning the process of creating multimedia. For example, PowerPoint uses the slideshow metaphor, as it relates to lecture presentations based on the (optical) slide projector. Multimedia authoring is one of the most complex authoring processes, and to some extent not as well grounded as those for the more traditional media. The following sections present two authoring models developed for supporting the process of authoring multimedia systems.

Conclusion

Authoring multimedia is much more complex than authoring traditional media. Collaboration between various parties is necessary for authoring any significant multimedia system. There are three multimedia-authoring dimensions: temporal, spatial and digital. These dimensions interact with each other in complex ways. The Movement Oriented Design (MOD) methodology uses story-telling concepts to develop the narrative of a multimedia system in the temporal dimension. Multimedia Design and Planning Pyramid (MUDPY) is model that supports systematic planning, design and production of multimedia projects. Multimedia project planning and design components include: Concept statement, Goals, Requirements, Target Audience, Treatment, Specifications, Storyboard, Navigation, Task Modeling, Content Gathering, Integration, and Testing. The MUDPY model exposes the relationship between these multimedia authoring aspects, suggests the order in which these should be tackled, and thus, supports cooperation between the members of a multimedia authoring team.

Authoring Tools

Selecting an authoring system is a complex procedure. Therefore, locating a number of standards that a multimedia authoring package could meet would mean simplifying the whole concept.

A substantial effort by Preclik (2002) produced the following variables:

(1) Variety of designed applications: Usually, less sophisticated authoring tools offer only the ability to design applications identical to one another. Of course, this is a result of the efforts to minimize package complexity which leads to a subsequent drop of the abilities’ standard.

(2) User interface: Normally, a good interface presents itself in two modes (at least): The “beginner mode,” with only the basic capabilities, and the “expert mode,” which offers all available features.

(3) Test questions: Rather than offering just plain multiple-choice questions, complex systems distinguish themselves by offering much more: hotspot questions, drag-and-drop questions, short-answer questions, true/false questions, etc.

List of some examined authoring tools

Program Company / Price OS

1 Authorware Macromedia $2,999 Windows/Mac

2 CBTMaster (Lessons) SPI $49 Windows

3 DazzlerMax Deluxe MaxIT Co. $1,995 Windows

4 Director Macromedia $1,199 Windows/Mac

5 EasyProf EasyProf €1,105 Windows

6 eZediaMX eZedia $169 Windows/Mac

7 Flash Macromedia $499 Windows/Mac

8 Flying Popcorn Parasys $149 Windows

9 Formula Graphics FGX $49.95 Windows

Multimedia

10 HyperMethod HyperMethod $190 (standard)-$390 (pro) Windows

11 HyperStudio Knowledge Adventure $69.95 Windows/Mac

12 InfoChannel Designer Scala $359 Windows

13 iShell 3 Tribeworks $495 Windows/Mac

14 Liquid Media SkunkLabs $140-$200 (academic) Windows

15 Magenta II Magenta $149 Windows

16 MaxMedia ML Software $50, Windows

17 Media Make&Go Sanarif €399 Windows

18 Media Mixer CD-Rom Studio $75 Windows

19 MediaPro MediaPro $99 Windows

20 Mediator 7 Pro Matchware $399 Windows

21 MetaCard MetaCard Co. $995 Windows/Mac/

UNIX

22 Motion Studio 3 Wisdom Software $39.95 Windows

23 MovieWorks Deluxe Interactive Solutions $99.95 Windows/Mac

24 MP Express Bytes of Learning $49.95 Windows/Mac

25 Multimedia Builder Media Chance $60 Windows

26 Multimedia Fusion ClickTeam $99 Windows

27 Multimedia Scrapbook Alchemedia, Inc. $89 Windows

28 MultimediaSuite $649 Windows

29 Navarasa Multimedia 4 Navarasa Multimedia $29.99 Windows

30 NeoBook NeoSoft Co. $199.95 Windows

31 ODS Players Optical Data Systems $229 Windows

32 Opus Pro Digital Workshop $249.95 Windows

Hypertext

Hypertext is a way of organizing material that attempts to overcome the inherent limitations of traditional text and in particular its linearity.

“Hypertext is the presentation of information as a linked network of nodes which readers are free to navigate in a non-linear fashion.

Hypertext Terms

This is a glossary of terms used within the WWW. In most cases, their use corresponds to conventional use in hypertext circles.

Anchor

An area to fix a graphical object so that its position relative to some other object remains the same during repagination. Frequently, for example, you may want to anchor a picture next to a piece of text so that they always appear together.

Annotation

A comment attached to a particular section of a document. Many computer applications enable you to enter annotations on text documents, spreadsheets, presentations, and other objects. This is a particularly effective way to use computers in a workgroup environment to edit and review work. The creator of a document sends it to reviewers who then mark it up electronically with annotations and return it. The document's creator then reads the annotations and adjusts the document appropriately.

Authoring

A term for the process of writing a document. “Authoring” seems to have come into use in order to emphasise that document production involved more than just writing.

Back Link

A link in one direction implied from the existence of an explicit link in the reverse direction.

Browser

A application which allows a person to read hypertext. The browser gives some means to viewing the contents of nodes, and of navigation from one node to another.

Button

It performs a special task when it is being pressed by the user. It is a trigger for the action.

Card

An alternative term for a node in a system (e.g. HyperCard, Notercards) in which the node sizze is limited to a single page of a limited size.

Client

A program which sends request services to the server.

Cyberspace

This is the “electronic” world as perceived on a computer screen; the term is often used in opposition to the “real” world.

Database

It is a collection of the data in a well manage manner, through the user can find the information.

Daemon

A program which runs independently of , for example the browser. Under UNIX “daemon” is used for “Server”.

Document

A document (noun) is a bounded physical representation of a body of information designed with the capacity (and usually intent) to communicate.

Domain

A group of computers and devices on a network that are administered as a unit with common rules and procedures. Within the Internet, domains are defined by the IP address. All devices sharing a common part of the IP address are said to be in the same domain.

External

A link to anode in a different database.

Host

A computer system that is accessed by a user working at a remote location. Typically, the term is used when there are two computer systems connected by modems and telephone lines. The system that contains the data is called the host, while the computer at which the user sits is called the remote terminal.

Hypermedia

An extension to hypertext that supports linking graphics, sound, and video elements in addition to text elements. The World Wide Web is a partial hypermedia system since is supports graphical hyperlinks and links to sound and video files. New hypermedia systems under development will allow objects in computer videos to be hyperlinked.

Index

A list of keys (or keywords), each of which identifies a unique record. Indices make it faster to find specific records and to sort records by the index field -- that is, the field used to identify each record.

Internal

A link to a node in a same databse.

Link

In hypertext systems, such as the World Wide Web, a link is a reference to another document. Such links are sometimes called hot links because they take you to other document when you click on them.

Navigation

A type of text-based Web site navigation that breaks the site into links of categories and sub-categories allowing major categories of information to be linked in a range of sequential order. Breadcrumb navigation is displayed to the user, so they can easily see exactly where that Web page is located within the Web site. While many types of Web sites use a breadcrumb navigation, it is becoming increasingly common for electronic commerce Web sites to display categories of products in this way.

Node

A unit of information

Graphics

Computer displays are made up from grids of small rectangular cells called pixels. The picture is built up from these cells. The smaller and closer the cells are together, the better the quality of the image, but the bigger the file needed to store the data. If the number of pixels is kept constant, the size of each pixel will grow and the image becomes grainy (pixilated) when magnified, as the resolution of the eye enables it to pick out individual pixels.

Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical equations, to represent images in computer graphics.

Vector graphics files store the lines, shapes and colors that make up an image as mathematical formulae. A vector graphics program uses these mathematical formulae to construct the screen image, building the best quality image possible, given the screen resolution. The mathematical formulae determine where the dots that make up the image should be placed for the best results when displaying the image. Since these formulae can produce an image scalable to any size and detail, the quality of the image is only determined by the resolution of the display, and the file size of vector data generating the image stays the same. Printing the image to paper will usually give a sharper, higher resolution output than printing it to the screen but can use exactly the same vector data file.